Dynamic modeling of the morphology of multiphase waterborne polymer particles

Multiphase waterborne polymer particles provide advantages in more demanding applications, and their performance depends on particle morphology. Currently, no dynamic model for the prediction of the development of the morphology of multiphase latex particles is available. In this work, a model was developed for the prediction of the dynamic development of the morphology of multiphase waterborne systems, such as polymer-polymer and polymer-polymer- inorganic hybrids

Dynamic modeling of the morphology of latex particles with in situ formation of graft copolymer

Modification of the polymer-polymer interfacial tension is a way to tailor-make particle morphology of waterborne polymer-polymer hybrids. This allows achieving a broader spectrum of application properties and maximizing the synergy of the positive properties of both polymers, avoiding their drawbacks. In situ formation of graft copolymer during polymerization is an efficient way to modify the polymer-polymer interfacial tension. Currently, no dynamic model is available for polymer-polymer hybrids in which a graft copolymer is generated during polymerization. In this article, a novel model based on stochastic dynamics is developed for predicting the dynamics of the development of particle morphology for composite waterborne systems in which a graft copolymer is produced in situ during the process

Particle Morphology

This chapter discusses the morphology of latex particles obtained mainly by (mini)emulsion polymerisation. It describes some applications of these particles, and discusses the factors that influence the particle morphology. Mathematical models that describe and predict the particle morphology as a function of polymerisation variables are presented along with some experimental examples. Structured polymer particles can be synthesized by chemical and physical methods. Among the physical methods, heterocoagulation and solvent evaporation have been used to produce capricious particle morphologies. Synthetic latexes are mainly used in applications (e.g., paints, adhesives, paper and coatings) that require the formation of a film. Film formation is described as consisting of three main processes: (i) evaporation of water to achieve the close-packing of particles, (ii) deformation of particles to fill all the void space, and (iii) interdiffusion of the polymer across particle interfaces to fuse particle boundaries

Impact of competitive processes on controlled radical polymerization

The kinetics of radical polymerization have been systematically studied for nearly a century and in general are well understood. However, in light of recent developments in controlled radical polymerization many kinetic anomalies have arisen. These unexpected results have been largely considered separate, and various, as yet inconclusive, debates as to the cause of these anomalies are ongoing. Herein we present a new theory on the cause of changes in kinetics under controlled radical polymerization conditions. We show that where the fast, intermittent deactivation of radical species takes place, changes in the relative rates of the competitive reactions that exist in radical polymerization can occur. To highlight the applicability of the model, we demonstrate that the model explains well the reduction in branching in acrylic polymers in RAFT polymerization. We further show that such a theory may explain various phenomena in controlled radical polymerization and may be exploited to design precise macromolecular architectures

Development of particle morphology in emulsion polymerization. 2. Cluster dynamics in reacting systems

A mathematical model for the development of particle morphology in emulsion polymerization has been developed. The polymer particles are considered to be a biphasic system comprising clusters of polymer 1 dispersed in a matrix of polymer 2. The model accounts for both polymerization and cluster migration. Polymerization of monomer 1 occurs both in the polymer matrix and in the clusters. The polymer 1 formed in the matrix diffuses instantaneously into the clusters. The clusters migrate toward the equilibrium morphology to minimize the free energy of the system. The driving forces for the motion of the clusters are the van der Waals interaction forces between the clusters and the aqueous phase and those between the clusters themselves. The effect of polymer matrix viscosity on the cluster motion is included. Illustrative simulations and comparisons with experimental data are presented

Development of particle morphology in emulsion polymerization. 1. Cluster dynamics

A mathematical model for cluster migration during the development of the particle morphology in emulsion polymerization has been developed. The motion of the clusters is due to the balance between the van der Waals forces and the viscous forces. Several illustrative calculations are presented including systems for which the final equilibrium morphologies were (i) core - shell, (ii) inverted core - shell, and (iii) occluded morphology. � 1995 American Chemical Society

Evidence of branching in poly(butyl acrylate) produced in pulsed-laser polymerization experiments

Branched poly(Bu acrylate) was obtained from pulsed-laser polymns. carried out in bulk and in soln. between -16 and +60 DegC. The predominantly short branches are formed by backbiting. The Arrhenius temp. dependence of the backbiting rate is calcd., and the activation energy of this process was found to be remarkably higher than that of propagation. Branching thus increases with temp. leading to broader SEC traces and difficulties in the accurate detn. of the rate of propagation. [on SciFinder (R)

Evidence of branching in poly(butyl acrylate) produced in pulsed-laser polymerization experiments

Branched poly(Bu acrylate) was obtained from pulsed-laser polymns. carried out in bulk and in soln. between -16 and +60 DegC. The predominantly short branches are formed by backbiting. The Arrhenius temp. dependence of the backbiting rate is calcd., and the activation energy of this process was found to be remarkably higher than that of propagation. Branching thus increases with temp. leading to broader SEC traces and difficulties in the accurate detn. of the rate of propagation. [on SciFinder (R)

Lack of prostaglandin involvement in the mitogenic effect of TSH on canine thyroid cells in primary culture.

The production of prostaglandin E2 (PGE2) by cultured dog thyroid cells was high in a serum-containing medium and low in a serum-free, completely defined medium. Thyrotropin (TSH) and epidermal growth factor (EGF), two mitogenic factors for these cells, did not stimulate PGE2 release. Indomethacin, at a concentration which completely inhibited PGE2 production, had no effect on thyroid cell multiplication and DNA synthesis stimulated by TSH and EGF. It is concluded that cyclooxygenase products are not involved in the proliferation of canine thyroid cells and its control by TSH.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe